 /*******************************************************************************
  * Copyright (c) 2000, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Common Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/cpl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.internal.contexts;

 import java.util.ArrayList ;
 import java.util.HashSet ;
 import java.util.List ;
 import java.util.Set ;

 import org.eclipse.ui.contexts.ContextEvent;
 import org.eclipse.ui.contexts.IContext;
 import org.eclipse.ui.contexts.IContextListener;
 import org.eclipse.ui.contexts.NotDefinedException;
 import org.eclipse.ui.internal.util.Util;

 final class Context implements IContext {

     private final static int HASH_FACTOR = 89;

     private final static int HASH_INITIAL = Context.class.getName().hashCode();

     private final static Set strongReferences = new HashSet ();

     private List contextListeners;

     private boolean defined;

     private boolean enabled;

     private transient int hashCode;

     private transient boolean hashCodeComputed;

     private String id;

     private String name;

     private String parentId;

     private transient String string;

     Context(String id) {
         if (id == null) throw new NullPointerException ();

         this.id = id;
     }

     public void addContextListener(IContextListener contextListener) {
         if (contextListener == null) throw new NullPointerException ();

         if (contextListeners == null) contextListeners = new ArrayList ();

         if (!contextListeners.contains(contextListener))
                 contextListeners.add(contextListener);

         strongReferences.add(this);
     }

     public int compareTo(Object object) {
         Context castedObject = (Context) object;
         int compareTo = Util.compare(defined, castedObject.defined);

         if (compareTo == 0) {
             compareTo = Util.compare(enabled, castedObject.enabled);

             if (compareTo == 0) {
                 compareTo = Util.compare(id, castedObject.id);

                 if (compareTo == 0) {
                     compareTo = Util.compare(name, castedObject.name);

                     if (compareTo == 0)
                             compareTo = Util.compare(parentId,
                                     castedObject.parentId);
                 }
             }
         }

         return compareTo;
     }

     public boolean equals(Object object) {
         if (!(object instanceof Context)) return false;

         Context castedObject = (Context) object;
         boolean equals = true;
         equals &= Util.equals(defined, castedObject.defined);
         equals &= Util.equals(enabled, castedObject.enabled);
         equals &= Util.equals(id, castedObject.id);
         equals &= Util.equals(name, castedObject.name);
         equals &= Util.equals(parentId, castedObject.parentId);
         return equals;
     }

     void fireContextChanged(ContextEvent contextEvent) {
         if (contextEvent == null) throw new NullPointerException ();

         if (contextListeners != null)
                 for (int i = 0; i < contextListeners.size(); i++)
                     ((IContextListener) contextListeners.get(i))
                             .contextChanged(contextEvent);
     }

     public String getId() {
         return id;
     }

     public String getName() throws NotDefinedException {
         if (!defined)
                 throw new NotDefinedException(
                         "Cannot get the name from an undefined context."); //$NON-NLS-1$

         return name;
     }

     public String getParentId() throws NotDefinedException {
         if (!defined)
                 throw new NotDefinedException(
                         "Cannot get the parent identifier from an undefined context."); //$NON-NLS-1$

         return parentId;
     }

     public int hashCode() {
         if (!hashCodeComputed) {
             hashCode = HASH_INITIAL;
             hashCode = hashCode * HASH_FACTOR + Util.hashCode(defined);
             hashCode = hashCode * HASH_FACTOR + Util.hashCode(enabled);
             hashCode = hashCode * HASH_FACTOR + Util.hashCode(id);
             hashCode = hashCode * HASH_FACTOR + Util.hashCode(name);
             hashCode = hashCode * HASH_FACTOR + Util.hashCode(parentId);
             hashCodeComputed = true;
         }

         return hashCode;
     }

     public boolean isDefined() {
         return defined;
     }

     public boolean isEnabled() {
         return enabled;
     }

     public void removeContextListener(IContextListener contextListener) {
         if (contextListener == null) throw new NullPointerException ();

         if (contextListeners != null) contextListeners.remove(contextListener);

         if (contextListeners.isEmpty()) strongReferences.remove(this);
     }

     boolean setDefined(boolean defined) {
         if (defined != this.defined) {
             this.defined = defined;
             hashCodeComputed = false;
             hashCode = 0;
             string = null;
             return true;
         }

         return false;
     }

     boolean setEnabled(boolean enabled) {
         if (enabled != this.enabled) {
             this.enabled = enabled;
             hashCodeComputed = false;
             hashCode = 0;
             string = null;
             return true;
         }

         return false;
     }

     boolean setName(String name) {
         if (!Util.equals(name, this.name)) {
             this.name = name;
             hashCodeComputed = false;
             hashCode = 0;
             string = null;
             return true;
         }

         return false;
     }

     boolean setParentId(String parentId) {
         if (!Util.equals(parentId, this.parentId)) {
             this.parentId = parentId;
             hashCodeComputed = false;
             hashCode = 0;
             string = null;
             return true;
         }

         return false;
     }

     public String toString() {
         if (string == null) {
             final StringBuffer stringBuffer = new StringBuffer ();
             stringBuffer.append('[');
             stringBuffer.append(defined);
             stringBuffer.append(',');
             stringBuffer.append(enabled);
             stringBuffer.append(',');
             stringBuffer.append(id);
             stringBuffer.append(',');
             stringBuffer.append(name);
             stringBuffer.append(',');
             stringBuffer.append(parentId);
             stringBuffer.append(']');
             string = stringBuffer.toString();
         }

         return string;
     }
 }

